This invention relates to a centrifugal pump. More particularly, this invention relates to a method and structure for forming a controlled air buffer cavity under pressure between a drive shaft seal and a rotating ring of slurry inside the pump housing.
A number of techniques are known for sealing slurry pumps. Mechanical seals are generally very expensive and are limited in their applications to light slurries. Dry gland expellers, as used in ASH pump R SRCTM pumps, are cheaper than mechanical seals and may be used in heavy slurry applications. However, dry gland expellers have limitations on sealing pressure. Moreover, dry gland expellers consume power and increase impeller overhang and shaft deflection.